| Electronics > Projects, Designs, and Technical Stuff |
| 78H05 |
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| Alex Eisenhut:
Recently dug up an old power supply I made, it uses a 78H05 regulator. All I could find is that's it's a "hybrid" part. I'm curious what that means. I'm guessing there's two dies in the TO-3, one is a pass transistor to allow the 5 amp output current? Not a lot of info on this part. |
| justanothercanuck:
They look fairly similar in design to a TO-220 LM7805. I can only guess that they're rated for higher amperage due to the internal bond wiring and enormous case partially acting as a heatsink, unless there's something in the datasheet schematic they're not telling us. :-// edit: how many pins does it have? If there's only 2 or 3, then it's a single output. |
| SeanB:
The original likely had a hybrid construction, using 2 dies on a ceramic substrate. One was the pass transistor, and the other is the rest of the regulator, with the ceramic substrate providing connection pads and isolation for the pass transistor, and probably with some deposited cermet resistors to use for the current sense and the voltage trim operation. Later versions with better processing got the lot onto a single die. Originally these were a very expensive part, as they had a ceramic inner, and had to be soldered to the die spreader with a low melting point solder after ceramic assembly. Pic of the inside from the NS datasheet is here http://www.datasheetspdf.com/PDF/78H05/623542/1 |
| Alex Eisenhut:
I figured it was just what it said, but that picture wasn't too clear to me. I guess you don't see too many hybrid 5 amp linear regulators these days. |
| Fraser:
I have a few of these in the spares drawer. I recall that when I was a student they seemed very expensive parts. As a result I only used one or two in DIY projects. Big chunky TO3 format, perfect for good heat transfer to the heatsink. Aurora |
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